This invention relates to explosive compositions, particularly to insensitive explosive compositions which exhibit steady-state detonation at reasonable critical diameter.
The unintentional detonation of high energy explosives has been responsible for a number of catastrophes, particularly in military use. The high potential for loss of life and destruction of equipment has prompted the military to impose severe limitations on the means and facilities for transport, handling and storage of such explosives. Military standards have been promulgated for insensitive high explosives (IHE) relating to performance and sensitivity to physical shock, fire, electrostatic discharge, and other hazards.
In view of these concerns, a variety of special formulations drawn to meeting military standards for IHE contracts has been developed, in attempts to combine high performance with low sensitivity to such influences as unintended impacts, electrostatic discharge, friction, and exposure to heat and flames of varying temperatures. The formulations developed to date range from certain types of melt-cast explosives to explosives which are combined with polymeric binders. Of the latter, pour-castable IHE's have been developed. For example, British patent No. 2 170 494, issued to Aerojet General Corporation, discloses an explosive composition which combines high performance with low sensitivity to external influences, yet has favorable mechanical properties and is capable of being poured into molds for casting.
Unfortunately, the usefulness of the melt-cast and pour-castable compositions is limited. The melt-cast compositions are limited by their physical and mechanical properties--i.e., some of the compositions are difficult to form into certain desired shapes, while others are susceptible to cracking under low temperature conditions, or have poor tensile or elongation properties or high modulus. On the other hand, state-of-the-art pour-castable compositions have excellent physical, mechanical and accidental ignition properties, but require cast diameters too large for sustaining detonation once deliberately initiated. Accordingly, the range of application of such compositions is limited, and few are satisfactory for use in general purpose munitions.